arbour vs arbor

arbour and arbor both are nouns.

Word	Noun	Adjective	Verb	Adverb
arbour	Yes	No	No	No
arbor	Yes	No	No	No

As nouns, arbour and arbor are synonyms defined as:

Other synonyms of arbour include bower, pergola.

arbour (noun)	arbor (noun)
a framework that supports climbing plants	a framework that supports climbing plants
	any of various rotating shafts that serve as axes for larger rotating parts
	tree (as opposed to shrub)